The present invention is drawn to the field of turbine engine components. More particularly, the present invention is drawn to a superalloy weld composition and a repaired component utilizing a superalloy weld composition.
The efficiency of gas turbine engines is dependent in part on the amount or degree of leakage of combustion gases between the turbine blades or buckets and the shroud of the turbine section of the engine. To minimize the gap, the tips are generally subjected to a precise machining operation. However, due to machining tolerances, thermal expansion differences between the components, and dynamic effects, typically some degree of rubbing between the tips and the shroud occurs.
Due to the rubbing contact, such as after extended service in the field, the base material of the blade is exposed, generally leading to corrosion and/or oxidation of the blade. Extended corrosion or oxidation leads to an increase in leakage between the blade and the shroud and consequent performance and efficiency losses. It has become commonplace to repair worn components as a cost-effective option to replacement, in view of the relative cost of turbine components such as blades or buckets. In a known repair technique, a weld wire formed of a weldable superalloy composition is used in a xe2x80x98build-upxe2x80x99 process to restore the blade to its original or near-original geometric configuration. For example, a nickel-base superalloy weld wire can be used in a tungsten arc welding process by making multiple passes over the tip region of a nickel-base superalloy blade. Following welding, the tip region is machined.
While there are numerous commercially available weld repair alloys, there continues to be a demand for further improved weld alloys, particularly, nickel-base weld alloys for nickel-base superalloy components. In this regard, the present inventors have recognized a need for a nickel-base superalloy that has improved oxidation resistance over state of the art repair alloys, and requisite high-temperature tensile strength and creep resistance. It is also desired to provide an alloy that has compositional uniformity to enable formation into a wire, and which has room temperature weldability (ductility). Furthermore, improvements in rupture lives of repair alloys are also sought.
One embodiment of the present invention calls a superalloy weld composition, including:
up to about 5.1 wt % Co;
about 7.2 to about 9.5 wt % Cr;
about 7.4 to about 8.4 wt % Al;
about 4.3 to about 5.6 wt % Ta;
about 0.1 to about 0.5 wt % Si;
about 0.1 to about 0.5 wt % Hf;
up to about 0.05 wt % C;
up to about 0.05 wt % B;
about 0 to about 2.2 Re;
about 2.7 to about 4.4 wt % W; and
balance Ni.
Another embodiment of the present invention is drawn to a repaired turbine engine component having a repaired region and an in-tact region. The repaired region has a composition as provided above.